Conversion of hydrocarbon oils



March 2, 1937. E. F. NELSON 2,072,123-

CONVERSION OF HYDROCARBON OILS Filed Feb. 8, 1952 FRACTIONATOR I I i7 M l COND sang! 2s 24 l RECEIVER FURNACE 2s, ,21

INVENTOR ATTOR Patented Mar. 2, 1937 UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS ware Application February 8, 1932, Serial No. 591,475

1 Claim. (01. 196-48) This invention relates more particularly to the conversion of crude petroleum, accompanied by conversion, in the same cracking system, of insufiiciently converted intermediate products of the process under independently controlled conversion conditions more severe than those to which the crude oil is subjected.

This invention is particularly directed to the treatment of crude petroleums such as those containing gasoline as well as higher boiling fractions whereby the total components of the crude are first subjected to conversion conditions such as will cause mild conversion or reforming of the motor fuel components to improve their antiknock value and conversion of the heavier components to produce additional products of good motor fuel characteristics, thence separating the heavy residual conversion products from the vaporous products, subjecting the vapors to fractionation whereby their insufiiciently converted components are condensed and separated from the motor fuel fractions and simultaneously subjecting said insufliciently converted components to further conversion in a separate heating element of the same system, under more severe conversion conditions than those to which the crude oil is subjected, for the purpose of producing increased yields of good quality motor fuel and commingling the products from both heating stages in the reaction zone of the system.

One specific form of apparatus in which the operation of the process may be accomplished is illustrated in the attached diagrammatic drawing, the following description of which includes a description of such operation.

Raw oil charging stock for the system may comprise any crude petroleum oil and preferably a crude consisting of a minor portion of gasoline and a major portion of higher boiling petroleum fractions including those within the boiling range of fuel oil or residual oils. The charging stock is supplied through line I and valve 2 to pump 3 from which it is fed through line 4 and valve 5 into heating element 6. Although not illustrated in the drawing, any well known means of preheating the raw oil prior to its introduction into heating element 6 may be employed. Heating element 6 is located in a furnace l capable of supplying the required heat to the oil undergoing conversion. A substantial superatmospheric pressure is preferably maintained in heating element 6 and the heated oil is discharged therefrom through line 8, valve 9 and line I 0 into reaction chamber ll.

Chamber H is also preferably maintained under super-atmospheric pressure and is preferably insulated against excessive loss of heat so that conversion, particularly of the vaporous products, may continue in this zone while the liquid products, which gravitate more rapidly to the bottom of the chamber, are withdrawn from the reaction zone without substantial further conversion. Both liquid and vaporous products may be simultaneously withdrawn from the lower portion of chamber ll through line l2 and valve l3 into chamber l4.

By means of valve I3, pressure may be substantially reduced in chamber l4 relative to that employed in chamber H, thus permitting further vaporization and cooling of the residual oil in chamber l4. Final separation of vaporous and residual liquid products is accomplished in chamber I4.

The residual liquid may be withdrawn from this zone through line 15 and valve Hi to cooling and storage or to any desired further treatment. Vapors are withdrawn from chamber I4 through line H and valve it to fractionation in fractionator I9.

Separation is effected in fractionator l9 between vapors of the desired end-boiling point and higher boiling insufiiciently converted materials, which latter are condensed in the fractionator to be withdrawn from the lower portion thereof through line 21) and valve 2| to pump 22. Pump 22 supplies these insufficiently converted intermediate products of the process through line 23 and valve 24 to heating element 25 where they are subjected to further conversion preferably under conditions more severe than those employed in heating element 6.

Furnace 25 of any suitable form supplies the required heat to heating element 25. The heated materials are discharged from this zone through line 27, valve 28 and line l 0 into reaction chamber ll, commingling in line 10 and in chamber II with the products resulting from treatment of the crude oil charging stock in heating element 6 to be subjected therewith to the subsequent reaction, vaporizing and fractionating steps already described. It will be understood that, when desired, products from heating elements 6 and 25 may be separately introduced into chamber H by well known means not illustrated in the drawing, instead of commingling in line H! prior to their introduction into the reaction chamber.

Vaporous products from the upper portion of fractionator l9, comprising uncondensable gas and motor fuel products of the process, including reformed gasoline from the crude and cracked gasoline resulting from conversion of the higher boiling crude oil components and further conversion of the reflux condensate are withdrawn through line 29 and valve 30 to be subjected to condensation and cooling in condenser 3|, distillate and gas from which passes through line 32 and valve 33 to be collected in receiver 34. Uncondensable gas may be released from the system through line 35 and valve 36. Distillate may be withdrawn from the receiver through line 31 and valve 38.

The primary heating element, wherein the raw oil charging stock is treated, preferably employs a conversion temperature of the order of 800 to 950 F. and a substantial superatmospheric pressure which may range, for example, from 100 to 500 pounds or more per square inch. The secondary heating element of the system, wherein reflux condensate from the fractionator is separately treated, may employ a temperature ranging, for example, from 900 to 1050 F. preferably at a substantial superatmospheric pressure of the order of 250 to 800 pounds or more per square inch. The reaction chamber of the system preferably employs a substantial superatmospheric pressure which may be equalized with that in the heating element employing the lowest pressure or may be somewhat reduced. Substantially reduced pressure relative to that employed in the reaction chamber is preferred in the chamber l4 and may range, for example, from substantially atmospheric to 100 pounds or more per square inch. The succeeding fractionating, condensing and collecting portions of the system may employ a pressure substantially equalized-with that in the chamber It or somewhat reduced relative thereto.

As a specific example of the operating conditions employed in the practice of the present invention and results obtainable from such operation, the charging stock for the process is a 30 A. P. I. gravity Mid-Continent crude oil containing approximately 12 per cent ofmaterial boiling below 400 F. The crude oil is subjected in the primary heating element of the system to a temperature of about 900 F. under a superatmospheric pressure of approximately 300 pounds per square inch. Substantially this same pressure is employed in the reaction chamber and a reduced pressure of approximately 50 pounds per square inch is employed in the succeeding vaporizing,

fractionating, condensing and collecting portions of the system. Reflux condensate from the fractionator of the system is subjected in the secondary heating element to a temperature of approximately 950 F. under a superatmospheric pressure of about 400 pounds per square inch. This operation may yield approximately 7'7 percent of motor fuel having an antiknock value approximately equivalent to an octane number of 75 and in addition there may be produced approximately '15 per cent of residual oil and about 800 cubic,

feet of gas per barrel of charging stock.

The foregoing specification and example will serve to indicate the nature of the invention and show its advantages as an improvement in the class of treatments to which it pertains but neither the specification nor the example are to be-considered as imposing undue limitation upon the broad scope of the invention.

I claim as my invention:

A process for producing anti-knock motor fuel which comprises passing crude petroleum con taining a substantial quantity of natural gasoline through a heating zone and heating the same therein to cracking temperature under superatmospheric pressure, discharging the thus heated crude, including its natural gasoline content, into the upper portion of an enlarged vertical reaction zone maintained under cracking conditions of temperature and superatmospheric pressure and passing both vaporous and liquid reaction products downwardly therethrough, removing the vaporous and liquid reaction products as a mixture from the lower portion of the reaction zone and separating the same into vapor and residue under a reduced pressure, fractionating the vapors to condense heavier fractions'thereof, heating resultant reflux condensate under superatmospheric pressure in a second heating zone to higher cracking temperature than the crude pe troleum in the first-mentioned heating zone and thence introducing the same to the upper portion of the reaction zone at a temperature and in sufficient amount to heat said natural gasoline to reforming temperature, retaining the natural gasoline in the reaction zone for a time period adequate to enhance its anti-knock value, and finally condensing the fractionated vapors.

EDWIN F. NELsoN. 

